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Delta‐opioid receptor immunoreactivity on astrocytes is upregulated during mitosis
Author(s) -
Thorlin Thorleif,
Persson P. Anders I.,
Eriksson Peter S.,
Hansson Elisabeth,
Rönnbäck Lars
Publication year - 1999
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/(sici)1098-1136(19990215)25:4<370::aid-glia6>3.0.co;2-j
Subject(s) - δ opioid receptor , receptor , downregulation and upregulation , opioid receptor , biology , opioid , agonist , opioid peptide , medicine , endocrinology , κ opioid receptor , microbiology and biotechnology , neuroscience , biochemistry , gene
Endogenous opioid peptides and opioid receptors are expressed by brain cells early during normal development, and exogenous opiate exposure in this period is known to affect brain cell proliferation and maturation. Despite the abundant evidence that opioids affect brain development, little is known about the mechanisms involved. In this study cortical astrocytes in primary culture were examined immunohistochemically by using antibodies against the opioid receptors. The immunoreactivity for δ‐opioid receptors was strongly upregulated during mitosis with an increase in immunostaining that started in early prophase and lasted through the M‐phase to cytokinesis. Similar effects could not be observed when antibodies against the μ‐ or κ‐opioid receptor subtypes were used. Cultured neurons and microglia presented a strong and homogenous immunostaining for the δ‐opioid receptor and no further upregulation of immunoreactivity could be detected in these cells. The presence of functional δ‐opioid receptors on the mitotic astrocytes was verified by using microspectrofluorometry for detection of δ‐opioid agonist induced changes in intracellular free calcium concentrations ([Ca 2+ ] i ). In these experiments fluo‐3/AM incubated cells showed a rapidly induced δ‐opioid agonist (DPDPE, 10 −6 M) evoked increase in [Ca 2+ ] i . These results suggest an upregulation of the δ‐opioid receptors that could represent a mechanism involved in the response to opioids in the developing brain. GLIA 25:370‐378, 1999. © 1999 Wiley‐Liss, Inc.